An article exposed to dynamic stresses and thus also to wear as well as noise development is for example a band, a strap, a belt, a hose, an air spring lobe, a compensator or a multilayered web, of which the belt in the form of a drive belt is of particular importance. The foundational body of a drive belt comprises a top ply as belt spine and a substructure with a force transmission zone. The following patent literature in particular is referenced for this: DE 38 23 157 A1, U.S. Pat. No. 8,262,523, WO 2005/080821 A1, US 2008/0032837, U.S. Pat. No. 3,981,206 and U.S. Pat. No. 5,417,618. A drive belt has elasticity because the foundational body and thus the top ply and the substructure contains a polymeric material having elastic properties, for which in particular the two groups of materials that are known as elastomers and thermoplastic elastomers (TPEs) are suitable here. Elastomers based on a vulcanized mixture of rubber are of particular importance.
The elastic foundational body further usually incorporates an embedded strength or tensile member, which may have one or more plies.
Drive belts in particular have a coating in the region of the force transmission zone in particular for noise reduction as well as enhanced abrasion resistance. This coating may be, for example, a flocked covering as described in DE 38 23 157 A1, or else a film covering as described in DE 10 2008 012 044 for example. It is similarly possible to use nonwovens where a loose fibrous web is thermally consolidated for example.
Typically, however, textile coverings are used as coating. Particularly textile coverings in the form of a woven fabric formed by intercrossing two sets of threads, viz., warp and weft, have recently become established in the marketplace. These are described inter alia in WO 2011/1103272A1 or DE 10 2007 062 285 A1.
Textile coverings are similarly known to take the form of a knitted fabric where a loop formed by a thread intermeshes into another loop. The knitted stitches thus obtained may be formed using one or more threads.
U.S. Pat. No. 8,262,523, for example, uses a warp-knitted fabric consisting of a first yarn, in particular of a polyamide (PA) or polyester (PES), and of a second yarn, in particular of a polyurethane (PU). The disadvantage is that test engines give rise to noise in the presence of moisture. The reason is the increased friction due to vulcanizate penetration through the knitted stitches, which additionally has an adverse effect on wear resistance.
A knitted textile covering is similarly disclosed in U.S. Pat. No. 3,981,206, EP 0 069 589 or U.S. Pat. No. 4,027,545. The disadvantage with this is, again, that test engines give rise to noise in the presence of moisture. Nor are the combination threads described therein durably stable, so the entire textile covering will frequently become brittle.
Relatively open-meshed knits useful as textile covering for drive belts are known inter alia from U.S. Pat. No. 6,572,505, U.S. Pat. No. 6,863,761, US 2008/0108466A1, US 2011/0269588 or U.S. Pat. No. 5,645,504. Adherence of the textile covering to the surface of the belt is improved by the openness of the mesh because gum/vulcanizate is able to penetrate through the knitted stitches during vulcanization. The result of this is a so-called ribbed construction, for example a 1×1 rib construction in U.S. Pat. No. 5,645,504 or a 2×2 rib construction in US 2008/0108466A1. The disadvantage with this is that the ribs themselves and the resultant vulcanizate penetration cause friction to increase, which in turn leads to noise production and also to adverse impacts on belt life.